More than 55 million people live with dementia worldwide, and nearly 10 million new cases are diagnosed every year, according to the World Health Organization (WHO). But a new study published in January by The Lancet finds global cases of dementia may triple by 2050 if countries do not provide prevention measures and effective treatments to address dementia risk factors.
“The number of people with dementia will increase a lot over the coming decades, largely due to aging of populations,” Theo Vos, co-author and professor at the Institute for Health Metrics and Evaluation at the University of Washington, told Seasons in an email.
In the findings of the study, researchers used a mathematical model – called Disease Modelling Meta-Regression – to estimate that the number of people with dementia would increase from 57 million cases globally in 2019 to 153 million cases in 2050. Specifically in the United States, dementia cases are expected to rise from 5.2 million to 10.5 million.
Researchers noted despite the large increases in the projected number of people living with dementia, age and sex remained stable between 2019 and 2050.
Furthermore, scientists say they expect more women to have dementia than men in 2050—primarily because it’s estimated that more women than men suffered with dementia worldwide in 2019. WHO reports that dementia has a disproportionate impact on women; in fact, women make up 65% of total deaths due to dementia.
Other key findings of the study
While age is the strongest risk factor for dementia and mainly affects older people, there’s a growing number of cases that start before the age of 65, as stated by Alzheimer’s Disease International.
The study finds there are many risk factors – including obesity, smoking, high blood sugar and low education – that have been linked to dementia.
With those risk factors in mind, researchers predict dementia cases will increase at different rates around the world.
Although there were increases for every country, the smallest increases were projected in high-income Asia Pacific countries by 53% and western Europe by 74%. The largest estimated increase in dementia rates was in North Africa and the Middle East by 367% and eastern sub-Saharan Africa by 357%. Scientists say these projected increases in cases could largely be caused by population growth and population aging.
“Demographic changes explain most of those differences,” said Vos. “Asia Pacific high-income countries such as Japan being the dominant country in the region in terms of population size will continue to be affected by further aging, but eastern/central Europe is forecast to have negative population growth.”
With regards to the U.S., Vos told Seasons they make separate estimates by state but not by income level.
“The region of high-income North America largely reflects the U.S. as Canada and Greenland are so much smaller population-wise,” he said. “In terms of risks, the U.S. has seen a greater increase in obesity and, consequently, diabetes compared to other parts of the world. In terms of demography, the U.S. increases in size due to migration and also is aging at a slower pace than say Germany, Italy or Japan.”
In the study, authors say there’s also a growing body of evidence from North America and Europe that suggests a decreasing trend in dementia rates—potentially due to more education and improvements in the management of cardiovascular disease and its risk factors.
Still, it remains unclear whether these trends will continue into the future or if they will extend to other geographical areas.
“However, all estimates agree that the absolute number of people affected by dementia will show large increases over time,” the authors said. “Globally, the number of people affected by dementia was estimated to have increased by 117% between 1990 and 2016, largely due to population aging.”
The World Health Organization declares people can reduce their risk of dementia by being physically active, refraining from smoking, avoiding harmful use of alcohol, eating a healthy diet, and maintaining healthy blood pressure, cholesterol and blood sugar levels.
But the authors of the study believe while those preventive measures are helpful, it comes down to education and creation of policies.
“We cannot change the demographics, the largest driver of change, at least not in the short run,” Vos said. “Change in education takes a long time to translate into change in dementia rates. However, we will continue to see improvements, particularly in parts of the world with the greatest improvements in access to education over the last decades.”
Other authors of the study say because there are no effective treatment options or therapies available, it will be necessary to plan for the increase in use of health and social care services to expand resources to support caregivers of individuals with dementia.
What comes next?
The authors of the study are working on quantifying more risk factors for dementia as part of the Global Burden of Disease study, with additional funding from Gates Ventures.
Vos said they will further examine the role of other risk factors – including physical inactivity, high blood pressure, high cholesterol, air pollution, depression, hearing loss, alcohol and head injury – and incorporate those findings in future related studies.